Panels often supports backlight as specified in a device tree.
Update the drm_panel infrastructure to support this to
simplify the drivers.
With this the panel driver just needs to add the following to the
probe() function:
err = drm_panel_of_backlight(panel);
if (err)
return err;
Then drm_panel will handle all the rest.
v2:
- Drop test of CONFIG_DRM_PANEL in header-file (Laurent)
- do not enable backlight if ->enable() returns an error
Signed-off-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Maxime Ripard <maxime.ripard@xxxxxxxxxxx>
Cc: Sean Paul <sean@xxxxxxxxxx>
Cc: Thierry Reding <thierry.reding@xxxxxxxxx>
Cc: Sam Ravnborg <sam@xxxxxxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
---
drivers/gpu/drm/drm_panel.c | 49 +++++++++++++++++++++++++++++++++++--
include/drm/drm_panel.h | 23 +++++++++++++++++
2 files changed, 70 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
index 2d59cdd05e50..35609c90e467 100644
--- a/drivers/gpu/drm/drm_panel.c
+++ b/drivers/gpu/drm/drm_panel.c
@@ -21,6 +21,7 @@
* DEALINGS IN THE SOFTWARE.
*/
+#include <linux/backlight.h>
#include <linux/err.h>
#include <linux/module.h>
@@ -196,13 +197,18 @@ EXPORT_SYMBOL(drm_panel_unprepare);
*/
int drm_panel_enable(struct drm_panel *panel)
{
+ int ret = 0;
+
if (!panel)
return -EINVAL;
if (panel->funcs && panel->funcs->enable)
- return panel->funcs->enable(panel);
+ ret = panel->funcs->enable(panel);
- return 0;
+ if (ret >= 0)
+ backlight_enable(panel->backlight);
+
+ return ret;
}
EXPORT_SYMBOL(drm_panel_enable);
@@ -221,6 +227,8 @@ int drm_panel_disable(struct drm_panel *panel)
if (!panel)
return -EINVAL;
+ backlight_disable(panel->backlight);
+
if (panel->funcs && panel->funcs->disable)
return panel->funcs->disable(panel);
@@ -289,6 +297,43 @@ struct drm_panel *of_drm_find_panel(const struct device_node *np)
EXPORT_SYMBOL(of_drm_find_panel);
#endif
+#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
+/**
+ * drm_panel_of_backlight - use backlight device node for backlight
+ * @panel: DRM panel
+ *
+ * Use this function to enable backlight handling if your panel
+ * uses device tree and has a backlight handle.
+ *
+ * When panel is enabled backlight will be enabled after a
+ * successfull call to &drm_panel_funcs.enable()
+ *
+ * When panel is disabled backlight will be disabled before the
+ * call to &drm_panel_funcs.disable().
+ *
+ * A typical implementation for a panel driver supporting device tree
+ * will call this function and then backlight just works.
+ *
+ * Return: 0 on success or a negative error code on failure.
+ */
+int drm_panel_of_backlight(struct drm_panel *panel)
+{
+ struct backlight_device *backlight;
+
+ if (!panel || !panel->dev)
+ return -EINVAL;
+
+ backlight = devm_of_find_backlight(panel->dev);
+
+ if (IS_ERR(backlight))
+ return PTR_ERR(backlight);
+
+ panel->backlight = backlight;
+ return 0;
+}
+EXPORT_SYMBOL(drm_panel_of_backlight);
+#endif
+
MODULE_AUTHOR("Thierry Reding <treding@xxxxxxxxxx>");
MODULE_DESCRIPTION("DRM panel infrastructure");
MODULE_LICENSE("GPL and additional rights");
diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
index ce8da64022b4..d30c98567384 100644
--- a/include/drm/drm_panel.h
+++ b/include/drm/drm_panel.h
@@ -28,6 +28,7 @@
#include <linux/errno.h>
#include <linux/list.h>
+struct backlight_device;
struct device_node;
struct drm_connector;
struct drm_device;
@@ -59,6 +60,10 @@ struct display_timing;
*
* To save power when no video data is transmitted, a driver can power down
* the panel. This is the job of the .unprepare() function.
+ *
+ * Backlight can be handled automatically if configured using
+ * drm_panel_of_backlight(). Then the driver do not need to implement the
+ * functionality to enable/disable backlight.
*/
struct drm_panel_funcs {
/**
@@ -132,6 +137,15 @@ struct drm_panel {
*/
struct device *dev;
+ /**
+ * @backlight:
+ *
+ * Backlight device, used to turn on backlight after
+ * the call to enable(), and to turn off
+ * backlight before call to disable().
+ */
+ struct backlight_device *backlight;
+
/**
* @funcs:
*
@@ -183,4 +197,13 @@ static inline struct drm_panel *of_drm_find_panel(const struct device_node *np)
}
#endif
+#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
+int drm_panel_of_backlight(struct drm_panel *panel);
+#else
+static inline int drm_panel_of_backlight(struct drm_panel *panel)
+{
+ return -EINVAL;
+}
+#endif
+
#endif
--
2.20.1
